The present invention relates to a resin sealed semiconductor device, and a method for manufacturing the same, which can ensure higher heat dissipation and higher quantity production.
In a recent demand for high integration density and high-speed characteristic, the semiconductor device needs a multi-pin structure and needs to be operated over a high frequency range. In such a high performance type semiconductor device, a semiconductor chip is mounted on a better heat dissipation bed in such a state as to expose the rear surface of the bed. By doing so, the semiconductor device achieves improved heat dissipation and high integration density and high performance throughout its whole system.
With reference to the drawing, explanation will be given below about the conventional resin sealed semiconductor device.
FIG. 1 is a plan view showing a conventional resin sealed semiconductor device of a first type, FIG. 2 is a bottom view thereof and FIG. 3 is a cross-sectional view thereof, taken along line III--III in a direction of arrows in FIG. 1.
A semiconductor chip 209 is bonded by a resin adhesive 213 to the central portion of a ceramics bed 201 as shown in FIG. 3. Electrodes 202 on the semiconductor chip 209 are electrically connected by wires 211 to leads 203 for signal transfer to an outside.
In this state, the bed 201 and semiconductor chips 209 are resin sealed and thus covered with the epoxy resin 215 except a bed surface side where no semiconductor chip is provided. This is done to improve heat dissipation.
The resin-sealing method of the resin-sealed semiconductor device is carried out by arranging the bed 201 in a mold, not shown, with the leads 203 held in place by a proper means and performing resin sealing. In this case, the forward end portions of the leads 203, that is, those portions of the leads connected to the wires 211, are arranged around the semiconductor chip 209.
The respective forward end portions of the leads 203 are placed within an upper surface area of the bed 201.
In the conventional resin-sealed semiconductor device of this first type, the bottom surface of the ceramics bed 201 area is made adequately larger than an area defined, over the bed, by the respective forward end surfaces of the leads 203 as viewed from the semiconductor chip 209 side, so that a greater external exposed area can be provided upon the resin sealing of the semiconductor device. This structure is excellent in that heat generated from the semiconductor chip 209 can be dissipated to an outside.
Since, however, the leads 203 and bed 201 are not respectively fixed in place, it is necessary to fix both by their associated members, respectively, upon the resin sealing of the semiconductor device. This requires a complex manufacturing process and prevents a quantity production.
With these in view, a second conventional resin-sealed semiconductor device has been conceived according to which both a bed and a plurality of leads are made of the same metal plate so as to achieve an improved quantity production.
FIG. 4 is a plan view showing a conventional resin-sealed semiconductor device of a second type, FIG. 5 is a bottom view thereof and FIG. 6 is a cross-sectional view thereof as taken along line VI--VI in a direction of arrows in FIG. 4.
A bed 301, leads 303 and tie bars 305 are punched out of a sheet of metal. A semiconductor chip 309 is bonded by a resin adhesive 313 to the central area of a bed 301. The leads 303 and electrodes 312 of the semiconductor chip 309 are electrically connected together by corresponding wires 311.
The bed 301, leads 303 and tie bars 305 are provided as an integral unit and, in this state, the bed 301 and semiconductor chip 309 are set in a mold, not shown, and sealed with an epoxy resin 315.
Further, in order to improve heat dissipation of the semiconductor chip, the bed 301 is exposed at a surface side where no semiconductor chip 309 is provided. In this resin-sealed semiconductor device, the bed and leads are formed by a punching method from the metal sheet and, since the bottom area of the bed 301 is made smaller than an area defined by the respective forward end portions of the leads 301 as viewed from the semiconductor chip 309 side, a smaller outer exposed area is provided upon the resin-sealing of the semiconductor device. As a result, the semiconductor chip 309 involves poor heat dissipation.